The Patent Abstract of Japan, Vol. 6, No. 116 (P-125) (994), Jun. 29, 1982, 8 JP-A-57 44 852, Mar. 13, 1982 discloses a method and an apparatus for revealing the solid state of an intentionally-congealed fluid in the pipe of a nuclear reactor. This process is not adapted for measurement of petroleum products.
The present invention concerns a procedure and device for measurement of the gelling of paraffinic petroleum products, especially crude products.
It is known that paraffinic crudes can form gels at temperatures approaching, or less than, 40.degree. C. This gelling phenomenon, when it occurs during production or transport, may lead to problems involving the restart-up of facilities. It is thus critically important to have available a method making it possible to determine what crudes are capable of gelling within a given temperature range and, as needed, to determine the minimum quantities of gelling-inhibitor or doping product needed to prevent the formation of gel.
Current conventional practice can measure the pour point of crudes (see Standard ASTM D-97 or AFNOR T60-103), this method consisting in cooling crude under determinate conditions in a special test tube equipped with a thermometer, and in looking to see whether, at each three-degree interval, the surface has or has not congealed. The temperature at which the surface of the crude congeals is the pour point.
It is also known how to measure, by differential caloric analysis, the incipient crystallization temperature of the crude, this latter corresponding, in fact, to a detectable exothermic phenomenon.
It is further known how to measure the rheological behavior of crudes, the flow properties of these latter ceasing newtonian behavior below a certain temperature, when paraffin crystals form within them.
However, none of these data, i.e., the measurement of the pour point, measurement of the incipient crystallization temperature, and the temperature at which rheological behavior changes, make it possible to know with certainty that operating difficulties will not occur in the event the crude is cooled below that temperature.